[FEATURE] Distro news (multi-distro)

[Firstp1ck]

Summary: Add a compact in-app news view for EndeavourOS, Manjaro, Garuda, and CachyOS, with filtering and a clear split between critical system updates (kernel/systemd/core) and general package news. Related planning: dev/IMPROVEMENTS/FEATURE_PRIORITY.md, dev/IMPROVEMENTS/news_feed_implementation.md, dev/WORKFLOWS/news_fetching_workflow.md.

Problem / motivation

Arch-based derivatives publish important announcements; users want them inside Pacsea with filtering and severity hints.

Goals

• Detect or let user select distro flavor; fetch appropriate feed(s) (RSS/Atom/JSON per distro).
• Present headlines + body in a reader panel; optional open-in-browser keybind.
• Classification: tag items affecting kernel/systemd/core as “system critical” when detectable from title/category/package lists; fallback heuristic with manual override not required in v1.

Recommended implementation

1) Reuse existing news plumbing

• Audit current news modules and HTTP/caching; extend with multi-source registry keyed by DistroId.

2) Sources

• Maintain a small table: EndeavourOS → URL, Manjaro → URL, etc., with versioned defaults; allow user override URLs in config for resilience.

3) Classification pipeline

• Rules: keyword lists (kernel, systemd, glibc, openssl, etc.) + optional RSS categories.
• Package correlation (stretch): if news references CVE or package name, cross-link to installed version if data available.

4) UX

• Filter chips: All | Critical | Pacman | AUR; search within cached items.
• Background refresh with TTL; show last updated timestamp.

Acceptance criteria

• Works offline with last cached fetch; shows stale indicator.
• Failing feed: per-source error, others still load.
• Respects --dry-run for any write (if caching to disk is considered mutating, document behavior consistent with app norms).

Testing

• Unit tests with recorded HTTP fixtures; no live network in CI.
• Parser tests for each feed shape you support.

Risks

• Feed format drift; keep parser tolerant and log parse failures.

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Tracking: dev/ROADMAP/OTHER_distro_news.md